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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 18 (1997), S. 2438-2452 
    ISSN: 0173-0835
    Keywords: Natural products ; Capillary electrophoresis ; Micellar electrokinetic capillary chromatography ; Chinese herbal preparations ; Alkaloids ; Toxins ; Illicit drugs ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Capillary electrophoresis (CE) and micellar electrokinetic chromatography were used for the separation of widely different compounds from natural materials including antibiotics, humic substances, flavonoids, isoflavonoids, illicit drugs, coumarins, alkaloids, steroids, Chinese herbal preparations, nicotine, caffeine, amphetamines, toxins such as aflatoxins B1, B2, G1, G2, mycotoxins, heptapeptide aflatoxins and others, ephedrine compounds, mineral elements, and natural compounds in biological samples. A discussion of sample extraction and clean-up and the advantages of using CE is also presented.
    Additional Material: 25 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0173-0835
    Keywords: Electrokinetic chromatography ; Charged cyclodextrins ; Geometric isomers ; Amino acids ; Dipeptides ; Chlorinated phenols ; Aflatoxins ; Polyacrylamide-coated columns ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Electrokinetic chromatography (EKC), with negatively-charged cyclodextrins (NCDs) added to the buffer, was conducted in polyacrylamide-coated columns under suppression of electroosmotic flow. The equations of migration and resolution for neutral solutes in this mode of chromatography, which for brevity we term NCD-EKC, are presented. The chiral sulfated cyclodextrin, β-CD-SBE (IV), used in this study is anionic over the entire pH range accessible to capillary electrophoresis, and the coated columns are stable and provide reproducible performance in the pH range 2.5-8.8. Optimum separation was obtained in the pH range where the solutes are neutral. The incorporation of an alkyl spacer between the sulfate ion and the rim of the cyclodextrin allows an unhindered approach and inclusion of neutral solutes in the cyclodextrin cavity. Solute migration time is inversely proportional to the concentration of the chiral selector. Separation (relative migration time difference) increases with decreasing chiral selector concentration and approaches a maximum, beyond which further decreases in chiral selector concentration result in broad peaks and loss of resolution. A chiral selector concentration of 1% in a 10 mM phosphate buffer produced excellent separation of amino acids and dipeptide enantiomers. In addition to being chiral selectors, cyclodextrins are also known as shape selectors. NCD-EKC is particularly suited for the separation of positional isomers of hydrophobic solutes. The separation of aflatoxin isomers and chlorophenol congeners is presented. In the separation of chlorophenols the more hydrophobic trichlorophenols eluted first and the least hydrophobic, phenol, eluted last.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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